The first Gunpla kits were sold in 1980 in Japan. Gunpla kits consist of several trays of parts or 'runners' that either snap-fit (most post-1990 models) or require glue (older models prior to 1990) to put together. The cover image on the box, or box art, is usually done by an illustrator with a picture illustration of the subject mecha design in action. All Gunpla are supplied with stickers and sometimes decals to apply extra colors and markings as seen in the show, movies, manga or video games. Smaller or lower grade kits often require paint to give the model a finished appearance. The kits range in different scales with the most popular scales being: 1:144 (approx 13 cm tall), 1:100 (approx 16–19 cm tall) and 1:60 (approx 30 cm tall).
Other scales include 1:200, 1:48, and the SD series. Since the first Gunpla release, there has been a constant improvement in quality design, material and manufacturing technique by Bandai. The basic kits of the late 1990s (routinely re-released by Bandai, with some exceptions) require cement and paint. These kits when completed, have very limited range of motion which renders them almost not poseable. These models were retrospectively called FG (). (HG) Later the quality of the moulding was improved and HG () level kits were introduced in.
These kits at either 1:144 or 1:100 scale, provide for better range of motion and greater poseability. It is important to note that the SEED and SEED DESTINY 1:100 scale models do not have HG listed anywhere on the box or manual, but they are considered HG in terms of quality.
(HGUC) The highly anticipated HG Universal Century series, commonly called the series, was released in May 1999. Created in an easy to collect 1:144 scale, it represented a chance to release versions of many Mobile Suits for the first time in kit form using refined designs and modern injection moulding technology. The high quality of the HGUC series makes it the rightful heir of the HG series released in the 1990s. New designs, with new mechanical improvements, continue to be introduced in the series even today. Furthermore, all modern 1/144 HG models, such as the Gundam SEED line, are built to the same quality of early HGUC models. Starting in 2010 the HGUC line incorporated mobile suits from the alternate timelines that had not received a HG.
In 2013 Bandai launched the 'All Gundam Project' in conjunction with the release of to release all lead Gundams with the universal joint technology in the High Grade line. (RG) In July 2010, Bandai introduced the 1:144 Real Grade (RG) line as part of the 'Gundam 30th Anniversary', which takes design elements from the Master Grade and Perfect Grade line such as an inner skeletal frame. This Gunpla line achieves the largest range of motion in each joint. (MG) The next level is designated as Master Grade (MG), which was introduced in 1995, and are only offered in 1:100 scale. These kits are manufactured using higher quality plastic and the resulting molds are of a greater standard. However, the model is more expensive, complicated and takes longer to construct.